Can a plagiarism checker detect translated text?

Yes, some can; however, this task is one of the hardest when it comes to finding plagiarism. A basic checker will only detect the text in its entirety by comparing exact pieces (or words) of the text to another identical piece of text. As long as the meaning of the sentence changes, a Spanish sentence translated into an English sentence would not be detected by a basic checker.

Advanced (or sophisticated) checkers use a process called semantic analysis to examine semantic elements (e.g. meaning of the word) of the text in order to be able to detect any translations of the source text in relation to its original version. An example would be that an advanced checker can compare the two languages against their respective sources and identify whether or not a particular text has been translated from one language into another. However, this is still not a foolproof method since heavy editing after translation, mixed language sources, and less common or longer languages can hinder a checker's ability to detect them.